Automatic cut-out



(No Model.) 4 Sheets-Sheet 1. G. E. SANFORD. AUTOMATIC GUT-OUT.

No. 484,865. Patented Oct. 25, 1892.

(No Model.) 4 Sheets-Sheet 2. C. E. SANFORD.

AUTOMATIC GUT-OUT. No. 484,865. Patented Oct. 25,1892.

(No Model.) 4 Sheets-Sheet 3. C. E. SANFORD.

AUTOMATIC GUT-OUT. No. 484,865, Patented 001:1. 25; 1892.

(No Mudel.) t V 4Sheets-Sheet 4. C. E. SANFORD.

AUTOMATIC GUT-OUT.

No. 484,865. Patented Oct. 25, 1892.

UNTTED; STATES PATENT OFFicE.

} CHARLES E. SANFORD, OF BROOKLYN, NEW YORK.

AUTOMATIC CUT-OUT.

SPECIFICATION forming part of Letters Patent No. 484,865, dated October25, 1892.

Application filed May 17, 1890. Serial No. 352.172- (No model.)

To aZZfwhom it may concern.-

Be it known that LOHARLEs E. SANFORD, of Brooklyn, New York, haveinvented certain Improvements in Self-Protecting Telephone and TelegraphProtectors, of which the following is a specification.

The improvements relate to a type of protectors for" telephone andtelegraph instruments analogous to that shown and described in LettersPatent of the United States No. 336,040, dated February 9, 1886, inwhich a single armature is employed as a circuit-closer.

and a high-resistance electro-magnet is combined with a relatively-lowresistance electromagnetfor thepurpose of increasing the sensitivenesswith which the apparatus operates to close aishunt-circuit around thetelephone or other instrument to be protected whenever the circuitbecomes charged with a current of abnormal? strength. I.

The present invention consists in the combination of a series of threeor more electromagnets the resistances of which diminish in a prescribedratio-and which are each provided with an armature arranged to act as acircuit-closer for closing a branch circuit, by means of whichabnormally-strongcurrents are not only shunted around the instrument tobe protected; but the more delicate electromagnets of the sericsthat isto say, those whose coils are composed of the finer wireare securelyguarded against the destructive efiects to which they would be subjectedif momentarily exposed to an abnormally-strong current.

The mode of operation of the apparatus will be easily understood onreference to the accompanying drawings, illustrating simple forms ofapparatus embodying the invention.

The drawings are as follows:

Figure 1 is a top view of the structure in which the electro-magnets areseparated from each other and which includes a symbolic representationof the circuits and the instruments to be protected. Fig. 2 is an endelevation of the structure shown in Fig. 1. Fig. 3 is a front elevationof the same. Fig. 4 is a transverse vertical section taken through theplane indicated by the dotted line or soon Fig. 3. Fig. 5 is a frontelevation exhibiting a modification in which the magnets are compactlygrouped together, and Fig. 6 is an end circuit. The coil D of theelectro-magnet D is composed of wire of prescribed fineness and of asufficient number of convolutions to insure a sufficiently-energeticmagnetization of its core D to enable the attractive force tooverbalance the strength of the armature-- spring d and swing itsarmature 01' against its stop 01 and thereby close the branch c1rcuit dwhenever the main circuit becomes charged with a current which in aprescribeddegree is in excess of the normal current employed to operatethe telephone. The current is thus split, the greater portion flowinginto the branch d and the smaller portion through the helix D of thefirst electro-magnet. The greater portion of the current is thus, bymeans of the branch d conducted to the ground without going throughthe'telephone B. If, however, there is a continued increase in thestrength of the current in the main cir cuit, then before the currentbecomes strong enough to burn out the fine-wire coil of the magnet D itenergizes the second magnet E sufficiently to overcome the retractilestrength of the armature-spring e, and to thus move the armature 6'against the stop 6 and thereby close the branch circuit e which, byaffording another path for the current, still further diminishes thequantity flowing through the fine-wire coil D. Again, when the currentin the main circuit has increased in strength to a further prescribeddegree the third electro-magnet, wound with a still coarser wire, isenergized sufficiently to enable its attractive force to counterbalancethe retractile spring f and move its armature f against the stop f,

and thereby close the third branch f by which another portion of thecurrent is conducted to the ground without being required to flowthrough the coils of the magnets. It will of course be understood that aseries of any desired number of electro-magnets may be thus arranged andoperated; but it will usually be found that three are sufficient forordinary purposes. For example, if it be assumed for the sake ofillustration that the circuit is to be normally charged with a currentof half an ampere then the first electro-magnet may be so adjusted thata current of, say, threefourths of an ampere will suffice to give itmagnetic energy sufficient to overcome the retractile force of itsarmature-spring and enable it to close the branch circuit 01 Assumngthat the wire of which the first armature is wound is to be guardedagainst a current of, say, one ampere, then the second electromagnet Ewill be so adjusted that a current of one ampere will enable it toattract its armature e and close the circuit e Again, assuming that theWire composing the helix E of the second electro-magnet is large enoughto carry with safety a current of notmore than ten amperes, then thethird electro-niagnet F will be so adjusted that a current of tenamperes will give it sufficient magnetic energy to overcome theretractile strength of its armature-spring f and move its armature jagainst its stop, and thereby close the branch circuit f The Wirecomposing the helix F of the third electro-magnet is assumed to besufficiently large to safely carry the heaviest current to which theapparatus will be exposed; but it will of course be seen that if desiredthere may be added to the series any additional number ofelectro-magnets, the coils of which may be composed of relativelylargerwires.

In order to secure a large contact area, the armature f has affixed toit the copper disk f, and the stop f upon which the periphery of thedisk f is adapted to bear, is a copper plate electrically connected withthe ground and projecting across the end of the electromagnet F, andperforated immediately opposite the core of the electro-magnet F.

As a measure of abundant caution, the main circuit may be provided withthe ordinary fusible section II.

'What is claimed as the invention is 1. The herein-describedself-protecting telephone and telegraph instrument protector, whichconsists of three or more electro-mag nets, the helices of whichrespectively vary in resistance in prescribed degrees and are connectedin series in the main circuit, which includes the telephone or telegraphinstrument to be protected, a number of normallyopen branch circuits tothe ground or shunts around the telephone or other instrument to beprotected, equaling the number of electromagnets employed, and a likenumber of armatures for respectively closing said branch or shuntcircuits successively when the helices of the magnet become charged withabnormal currents of prescribed strength.

2. The electro-magnet F and the stop f the same consisting of a metallicplate electrically connected with the ground and projecting across theend of the electro-magnet F and having a perforation immediatelyopposite the core of the said electro-magnet, in combination with thearmature f and the disk f carried upon said armature for closing thebranch circuitf by the contact of its periphery with the face of thesaid stop f, as set forth.

CHARLES E. SANFORD.

Witnesses:

A. M. JONES, J. E. BURNS.

